Bearing systems

ABSTRACT

A bearing system includes a barrier, a bearing unit housing, and a bearing unit for conveying a drive through the barrier. The bearing unit housing defines an opening through the barrier extending between the first and second sides of the barrier. The bearing unit housing extends along an axis and includes a contact portion extending parallel to the axis which contacts a contact portion of the bearing unit extending parallel to the axis. The length of the contact portion of the bearing unit housing exceeds the distance along the axis between the part of the contact portion of the bearing unit nearest the first side of the barrier and the part of the contact portion of a replacement bearing unit nearest the second side of the barrier. The invention offers particular advantages in maintaining containment provided by the barrier during barrier replacement.

This invention concerns improvements in and relating to bearing systems,particularly, but not exclusively, in relation to bearing units withinsuch systems that require occasional replacement whilst maintainingcontainment of an associated environment.

Many situations require motive power to be delivered into a hazardousenvironment whilst maintaining containment for the environment. Placingthe motive power source in the hazardous environment is undesirable asit is exposed to the hazardous environment and is not easily accessibleas a result. It is possible to provide the motive power source outsidethe hazardous environment, but then suitable means must be provided tobring the power into the environment whilst maintaining containment. Insuch situations the transit between the hazardous environment andsurrounding environment a bearing unit is often provided. Due to routinewear and tear the bearing unit may need replacement on occasions andthis causes a potential break in containment whilst the replacement iseffected.

The present invention has amongst its aims the replacement of bearingunits whilst maintaining containment for a hazardous environment.

According to a first aspect of the invention we provide a bearing systemincluding a barrier, a bearing unit housing and a bearing unit forconveying a drive through the barrier, wherein the bearing unit housingdefines an opening through the barrier extending between first andsecond sides of the barrier, the bearing unit housing extends along anaxis, the bearing unit housing includes a contact portion extendingparallel to the axis which contacts a contact portion of the bearingunit extending parallel to the axis, the length of the contact portionof the bearing unit housing exceeds the distance along the axis betweenthe part of the contact portion of the bearing unit nearest the firstside of the barrier and the part of the contact portion of a replacementbearing unit nearest the second side of the barrier.

The first aspect may further provide that the length of the contactportion of the bearing housing exceeds the distance between the leadingpart of the contact portion of the bearing unit and the part of thebearing unit which extends furthest from the first side of thecontainment barrier and is integral with the bearing unit.

According to a second aspect of the invention we provide a bearingsystem including a barrier, a bearing unit housing and a bearing unitfor conveying a drive through the barrier, wherein the bearing unithousing defines an opening through the barrier extending between firstand second sides of the barrier, the bearing unit housing extends alongan axis, the bearing unit housing includes a contact portion extendingparallel to the axis which contacts a contact portion of the bearingunit extending parallel to the axis, and wherein the length of thecontact portion of the bearing housing exceeds the distance between theleading part of the contact portion of the bearing unit and the part ofthe bearing unit which extends furthest from the first side of thebarrier and is integral with the bearing unit.

The second aspect may further provide that the length of the contactportion of the bearing unit housing exceeds the distance along the axisbetween the part of the contact portion of the bearing unit nearest thefirst side of the barrier and the part of the contact portion of areplacement bearing unit nearest the second side of the barrier.

The first and/or second aspects of the invention may provide one or moreof the following features, options or possibilities.

The bearing system may include one or more of a motor, one or more driveshafts connecting the motor to the bearing unit, one or more driveshafts connecting the bearing unit to the equipment to be driven. Inparticular a first drive shaft, connected directly or indirectly, to themotor may be connected to a second drive shaft connected to the bearingunit or to the drive shaft of the bearing unit, directly by means of acoupling and preferably a flexible coupling. In particular the bearingunit may be connected to the equipment to be driven, directly orindirectly, using a further drive shaft having at both ends releasablecouplings, particularly couplings of the two half type. It isparticularly preferred that the drive shaft of the bearing unit isconnected to the further drive shaft using such two half couplings.Preferably the motor is provided to the first side of the barrier andthe equipment to be driven is provided to the second side of thebarrier. Preferably the further drive shaft is longer than the driveshaft of the bearing unit.

The barrier may be of metal or concrete. The barrier particularlyprovides physical containment for radioactive material, such asplutonium oxides or uranium oxides. The barrier may provide radiologicalshielding. Preferably the hazardous environment is on the second side ofthe barrier. Preferably an ambient environment is on the first side ofthe barrier.

Preferably the barrier is provided with an aperture which is fullysurrounded by the bearing unit housing. The bearing unit housing may bereleasably fastened to the barrier. Preferably the releasable fasteningsare bolts. Preferably the bolts are introduced from the first side ofthe barrier. Preferably the holes receiving the bolts do not penetratefrom the first to the second side of the barrier. The bearing unithousing may be retained on the barrier by fasteners engaging a flangeprojecting from the bearing unit housing, particularly a flangeextending substantially perpendicular to the axis of the bearing system.

Preferably the bearing unit housing includes a body portion. The flangesmay be connected to the body portion. Preferably the body portionextends generally along the axis. It is particularly preferred that thebody portion defines a cylindrical internal space, most preferably aright cylinder with an axis corresponding to the axis of the system.Preferably the bearing unit housing is provided with an apertureextending from the first to the second side of the barrier which is ofcircular cross section and preferably of constant radius throughout atleast the mid 90% of its length. An increased radius may be provided fora portion of the bearing unit housing closest to the first and/or secondsides of the barrier. The increased radius portion may be chamfered orof truncated conical shape. Preferably the external configuration of thebody portion of the bearing unit housing is cylindrical.

Preferably the bearing unit is in sliding contact with the internalsurface of the bearing unit housing. Sliding contact around the entireperiphery for at least a portion of the bearing unit is preferablyprovided. Preferably this portion extends for at least 80% and morepreferably at least 90% of the axial length of the bearing unit.Preferably the bearing unit has a cylindrical external profile.Preferably the bearing unit has a constant radius throughout at least80% and more preferably at least 90% of its axial length. The bearingunit may have a reduced radius towards the ends nearest the first and/orsecond sides of the barrier.

The bearing unit may include a cylindrical body portion to which an endplate is fastened at each end. The end plates are preferably fastened bybolts.

The bearing unit preferably accommodates a centrally provided driveshaft. Preferably the drive shaft is supported by a pair of bearings.Preferably one bearing is provided towards one end of the bearing unit,and the other bearing is provided towards the other end of the bearingunit. Preferably one or more seals are provided between the first sideand the bearing closest thereto and/or between the second side and thebearing closest thereto. O-rings and other seals could be used for thispurpose.

Preferably the drive shaft extending through the bearing unit isprovided with a locking nut to maintain it in position.

Preferably the drive shaft extending through the bearing unit isprovided with a male portion at one end, and a female portion at theother end. The male portion may be provided by a portion of the driveshaft of greater cross-section compared with the female portion.Preferably the male portion has a greater external radius than thefemale portion. Preferably the male portion is provided with a recessadapted to receive and cooperate with at least a part of the femaleportion.

Preferably the bearing unit housing is provided with an end plate on thefirst side of the barrier. Preferably the end plate engages the body ofthe bearing unit housing by means of one or more releasable fasteners.Preferably one or more releasable fasteners pass through the end plateand engage the bearing unit. Preferably the end plate is provided withan aperture through which the drive, particularly the drive shaft of thebearing unit passes.

One or more of the drive shafts and/or couplings on the second side ofthe barrier may be provided within an enclosure, such as a guard.

Preferably the axis of the bearing unit housing corresponds to the axisof the drive through the bearing unit.

Preferably the contact portion of the bearing unit housing extendsaround the entire profile thereof for at least a part of the lengththereof. Preferably the contact portion of the bearing unit housingextends for at least 75% and more preferably 80% and ideally 90% of thelength of the bearing unit housing along the length of the axis.

Preferably the contact portion of the bearing unit extends around theentire circumference thereof for at least a part of the length thereof.Preferably the contact portion of the bearing unit extends for at least75% and more preferably 80% and ideally 90% of the length of the bearingunit along the length of the axis.

The part of the bearing unit which extends furthest from the first sidemay be the end of the integral drive shaft thereof. Preferably this endis provided with a female portion. Preferably the overall length of thebearing unit along the axis is less than the overall distance along theaxis between the barrier surface on the second side of the barrier andthe end nearest the second side of the barrier of the drive shaftadjacent to the drive shaft connected to the bearing unit. Morepreferably the overall length of the bearing unit is less than thedistance between the second side of the barrier and the part of thecoupling retained on the drive shaft adjacent to the drive shaftconnected to the bearing unit.

Preferably the bearing unit incorporates a seal for life bearings.Preferably the bearing unit is housed in stainless steel. The bearingunit housing may be provided with one or more mounts for accelerometers.

Preferably the end surface of the bearing unit closest to the secondside of the barrier in use is flush with the surrounding part of thebearing unit housing and/or surface of the barrier.

According to a third aspect of the invention we provide a method ofreplacing a bearing unit in a bearing system, the bearing systemincluding a barrier, a bearing unit housing and a bearing unit forconveying a drive through the barrier, the bearing unit housing definingan opening through the barrier extending between first and second sidesof the barrier, the bearing unit housing extending along an axis, thebearing unit housing including a contact portion extending parallel tothe axis which contacts a contact portion of the bearing unit extendingparallel to the axis, the method including

-   -   disconnecting the bearing unit in the bearing system from the        drive to and from the bearing unit,    -   introducing a replacement bearing unit into abutment with the        bearing unit and advancing the replacement bearing unit into the        bearing unit housing from the first side of the barrier and        displacing the bearing unit towards the second side of the        barrier    -   during displacement, contact being maintained between at least a        part of a contact portion of the bearing unit and at least a        part of a contact portion of the bearing unit housing until        contact occurs between at least a part of a contact portion of        the replacement bearing unit and at least a part of a contact        portion of the bearing unit and    -   removing the bearing unit from the bearing unit housing on the        second side of the barrier and connecting the bearing unit to        the drives to and from the bearing unit.

The third aspect of the invention may include one or more of thefeatures, options or possibilities set out elsewhere in this documentincluding those set out above in relation to the first and secondaspects of the invention.

Preferably the bearing unit is replaced by an equivalent replacementbearing unit.

Preferably the bearing system is electrically isolated prior to workingthereon.

The bearing unit may be disconnected from the drives to the bearing unitby removing the flexible coupling and/or drive shaft linking theflexible coupling to the bearing unit and/or the drive shaft linking theflexible coupling to the motor and/or by moving the motor.

The drive from the bearing unit may be disconnected by removing thedrive shaft adjacent to the drive shaft of the bearing unit, potentiallytogether with the coupling or a portion thereof connecting those driveshafts together and potentially and alternatively together with theremoval of at least part of the coupling connecting that drive shaft tothe subsequent drive shaft of the bearing system.

Preferably the replacement bearing unit is introduced along the axis ofthe bearing unit housing. Preferably the part of the drive shaft of thereplacement bearing unit closest to the first side of the barrierengages with the part of the bearing unit furthest from the second sideof the barrier and ideally with the drive shaft thereof. Preferably thereplacement bearing unit is provided with one of a male or female partclosest to the first side of the barrier and the bearing unit isprovided with the converse of a male or female portion of the partthereof furthest from the second side of the barrier. Preferablyintroduction of the replacement bearing unit brings the drive shaftthereof into abutment with the drive shaft of the bearing unit. Theleast part of the contact portion of the bearing unit maintained incontact with the contact portion of the bearing unit housing may be 20%or more of the maximum possible contact portion of the bearing unit whenthe contact portion of the replacement bearing unit first contacts thecontact portion of the bearing unit.

Preferably the replacement bearing unit is introduced along the axis ofthe bearing unit housing. Preferably the part of the drive shaft of thereplacement bearing unit closest to the first side of the barrierengages with the part of the bearing unit furthest from the second sideof the barrier and ideally with the drive shaft thereof. Preferably thereplacement bearing unit is provided with one of a male or female partclosest to the first side of the barrier and the bearing unit isprovided with the converse of a male or female portion of the partthereof furthest from the second side of the barrier. Preferablyintroduction of the replacement bearing unit brings the drive shaftthereof into abutment with the drive shaft of the bearing unit. Theleast part of the contact portion of the bearing unit maintained incontact with the contact portion of the bearing unit housing may be 20%or more of the maximum possible contact portion of the bearing unit whenthe contact portion of the replacement bearing unit first contacts thecontact portion of the bearing unit.

Preferably the bearing unit is removed along the axis of the bearingunit housing. The at least part of the contact portion of thereplacement bearing unit in contact with the contact portion of thebearing unit housing may be 20% or more of the maximum possible contactportion of the bearing unit when the contact portion of the bearing unitbreaks contact with the contact portion of the bearing unit.

The bearing unit may be removed from the bearing unit housing on thesecond side of the barrier by a manipulator or other operative componenton the second side of the barrier. The manipulator or operativecomponent is preferably used to remove and connect the drive shaftand/or coupling on the second side of the barrier. The bearing unit maybe removed from between the second surface of the barrier and the driveshaft adjacent to the drive shaft connected, in use, to the bearingunit.

The bearing unit may be retained within the second side of the barrieror may be removed therefrom by a further opening in the barrier providedelsewhere.

Embodiments of the invention will now be described, by way of exampleonly, with reference to the accompanying drawings in which:

FIG. 1 illustrates a bearing system in assembled configuration;

FIG. 2 a illustrates an initial configuration during replacement of abearing unit in the bearing system;

FIG. 2 b illustrates a subsequent configuration during the replacementof the bearing unit in the bearing system; and

FIG. 3 illustrates a still subsequent configuration illustrating initialintroduction of the replacement bearing unit into the bearing system.

FIG. 1 illustrates one example of a bearing system 1 designed to conveymotive power from a power source, such as a motor 3, to equipment 5needing such power. The equipment 5 is within a hazardous environment 7which is separated from the external environment 9 by containmentbarrier 11.

The rotation of motor drive shaft 13 passes through flexible coupling 15to first shaft 17. The first shaft 17 is provided with a reduceddiameter male portion 19 which cooperates with female portion 21 ofsecond drive shaft 23. The drive shaft 23 passes through the bearingunit 25 and ends at male portion 27. The male portion 27 is connected toa first half 29 of a coupler 31, the second half 33 of the coupler 31connecting to a third drive shaft 35. The third drive shaft 35 connectsto a first half 37 of a further coupler 39, with the second half 41 ofthe further coupler 39 connecting to an equipment drive shaft 43 whichlinks directly or indirectly to the equipment 5. The coupler 31, furthercoupler 39, their linking third drive shaft 35 and the projecting maleportion 27 of the second drive shaft 23 are enclosed within guard 43.

The bearing unit 25 is in the general form of a cylindrical component 45defined by a cylinder 47, first end plate 49 and second end plate 51.The end plates 49, 51 are connected to the cylinder 47 by bolts 53. Thebearings 55, 57 are provided on the cylinder 47 and are lifetime sealedby dust and oil seals 59, 61 to avoid any loss or contamination of thelubricant within the assembly 25. A locknut 63 is provided to apply aforce onto the bearing 55.

The bearing unit 25 is mounted on the containment barrier 11 by ahousing 65. The housing 65 is mounted to the containment barrier 11 bymeans of bolts 67 which do not penetrate the containment barrier 11. Thehousing 65 is formed by a cylinder 69, of corresponding internaldiameter to the outside diameter of the cylinder 47, together with aradial extension 71 which receives the bolts 67. An end plate 73 isfastened to the cylinder 69 by bolts 75 and to the bearing unit 25 bybolts 77 to retain the bearing unit 25 in the desired position.

In this configuration power can be conveyed from the safe environment 9to the hazardous environment 7, but with a full seal between the two.

If the bearing unit 25 develops a problem, or more usually, reaches itsscheduled replacement time, then the following sequence can be used toreplace the bearing unit 25 whilst maintaining the seal.

As an initial step in the replacement method the power to the bearingsystem 1 is isolated to allow safe working on it.

As one step in the method, the guard 43 is then removed using amanipulator within the hazardous environment and placed to one side. Thehalf 33 of coupler 31 is then detached from half 29 and half 37 ofcoupler 39 is then detached from half 41 to allow the removal of thedrive shaft 35. This drive shaft 35 is then placed to one side withinthe environment 7. The longer length of the drive shaft 35 compared withthe length of the bearing unit 25 means that the drive shaft 35 removalgives sufficient space to remove the bearing unit by displacing it intothe environment 7. The remaining half 29 of the coupler 31 is thenremoved and placed to one side also. The result of this step is shown inFIG. 2 a.

Following or previous to this step the flexible coupling 15 is removed.This may be accompanied by removal of the one or more of the driveshafts 13, 17 or motor 3 to allow room for the replacement bearing unit25X to be introduced. Once this step is completed the end plate 73 isremoved following release of the bolts 75 and 77. The end plate 73 isput to one side in environment 9. The result of this step is shown inFIG. 2 b.

In this state the seal is maintained but the bearing unit 25 is free tomove in the housing 65.

As illustrated in FIG. 3, the new bearing unit 25X can now be broughtinto position in line with the existing bearing unit 25 and the housing65. The new bearing unit 25X has a drive shaft 27X mounted on it whichhas a male end portion so that it cooperates with the female portion 21of the drive shaft on the bearing unit 25. Advancing the bearing unit25X from the environment 9 into the housing 65 pushes the bearing unit25 into the hazardous environment 7. The leading edge 100 of the bearingunit 25X has a reduced diameter compared with the internal diameter ofthe housing 65 to assist insertion. The axial extent Y of the housing 65is such that the leading edge 100 of the bearing unit 25X enters thecylinder 69 before the trailing edge 102 of the bearing unit 25 enterthe environment 7; indeed, as is shown a significant overlap exists.Eventually continued advancement of the bearing unit 25X pushes thebearing unit 25 so far into the environment 7 that its trailing edge 102comes clear of the housing 65. At this time the manipulator within theenvironment 9 is used to move the bearing unit 25 to one side, itsuseful life having finished. The trailing edge 102 of the bearing unit25 has a reduced diameter compared with the internal diameter of thehousing 65 to assist removal. The bearing unit 25 can be removed fromthe hazardous environment 7 using contaminated item removal procedures,if desired, or left there until the environment and its contents aredecommissioned. With the bearing unit 25 removed, the bearing unit 25Xcan then be positioned correctly, with the leading edge 100 flush withthe internal surface 104, within the housing 65 and the bearing system 1can be reassembled.

Reassembly involves attaching the back plate 73, bolts 75, 77, flexiblecoupling 15 (and possibly accompanying drive shafts 13, 17 and/or motor3), coupling half 29, drive shaft 35 and accompanying coupling halves 33and 37, before the guard 43 is repositioned and fastened. The bearingsystem 1 is then ready for further use, but the integrity of the sealbetween the hazardous environment 7 and safe environment 9 is maintainedthroughout.

1. A system comprising: a barrier, a bearing unit housing and a bearingunit for conveying a drive through the barrier, wherein the bearing unithousing defines an opening through the barrier extending between firstand second sides of the barrier, the bearing unit housing extends alongan axis, the bearing unit housing includes a contact portion extendingparallel to the axis which contacts a contact portion of the bearingunit extending parallel to the axis, the length of the contact portionof the bearing unit housing exceeds the distance along the axis betweenthe part of the contact portion of the bearing unit nearest the firstside of the barrier and the part of the contact portion of a replacementbearing unit nearest the second side of the barrier.
 2. A systemaccording to claim 1 in which the length of the contact portion of thebearing housing exceeds the distance between the leading part of thecontact portion of the bearing unit and the part of the bearing unitwhich extends furthest from the first side of the containment barrierand is integral with the bearing unit.
 3. A bearing system, comprising:a barrier, a bearing unit housing and a bearing unit for conveying adrive through the barrier, wherein the bearing unit housing defines anopening through the barrier extending between first and second sides ofthe barrier, the bearing unit housing extends along an axis, the bearingunit housing includes a contact portion extending parallel to the axiswhich contacts a contact portion of the bearing unit extending parallelto the axis, and wherein the length of the contact portion of thebearing unit housing exceeds the distance between the leading part ofthe contact portion of the bearing unit and the part of the bearing unitwhich extends furthest from the first side of the barrier and isintegral with the bearing unit.
 4. A bearing system according to claim 3in which the length of the contact portion of the bearing unit housingexceeds the distance along the axis between the part of the contactportion of the bearing unit nearest the first side of the barrier andthe part of the contact portion of a replacement bearing unit nearestthe second side of the barrier.
 5. A bearing system according to claim 3in which the bearing system includes one motor, one or more drive shaftsconnecting the motor to the bearing unit and one or more drive shaftsconnecting the bearing unit to the equipment to be driven.
 6. A bearingsystem according to Claim 3 in which the bearing unit housing isprovided with an aperture extending from the first to the second side ofthe barrier which is of circular cross section and is of constant radiusthroughout at least the mid 90% of its length.
 7. A bearing systemaccording to claim 3 in which an increased radius is provided for aportion of the bearing unit housing closest to the first and/or secondsides of the barrier.
 8. A bearing system according to claim 3 in whichthe bearing unit has a constant radius throughout at least 80% of itsaxial length and the bearing unit has a reduced radius towards the endsnearest the first and/or second sides of the barrier.
 9. A bearingsystem according to any preceding claim 3 in which the drive shaftextending through the bearing unit is provided with a male portion atone end, and a female portion at the other end.
 10. A method ofreplacing a bearing unit in a bearing system, the bearing systemincluding a barrier, a bearing unit housing and a bearing unit forconveying a drive through the barrier, the bearing unit housing definingan opening through the barrier extending between first and second sidesof the barrier, the bearing unit housing extending along an axis, thebearing unit housing including a contact portion extending parallel tothe axis which contacts a contact portion of the bearing unit extendingparallel to the axis, the method comprising: disconnecting the bearingunit in the bearing system from the drive to and from the bearing unit;introducing a replacement bearing unit into abutment with the bearingunit and advancing the replacement bearing unit into the bearing unithousing from the first side of the barrier and displacing the bearingunit towards the second side of the barrier; during displacement,contact being maintained between at least a part of a contact portion ofthe bearing unit and at least a part of a contact portion of the bearingunit housing until contact occurs between at least a part of a contactportion of the replacement bearing unit and at least a part of a contactportion of the bearing unit; and removing the bearing unit from thebearing unit housing on the second side of the barrier and connectingthe bearing unit to the drives to and from the bearing unit.
 11. Amethod according to claim 10 in which the bearing unit is disconnectedfrom the drives to the bearing unit by removing the flexible couplingand/or drive shaft linking the flexible coupling to the bearing unitand/or the drive shaft linking the flexible coupling to the motor and/orby moving the motor.
 12. A method according to claim 10 in which thedrive from the bearing unit is be disconnected by removing the driveshaft adjacent to the drive shaft of the bearing unit, potentiallytogether with the coupling or a portion thereof connecting those driveshafts together and potentially and alternatively together with theremoval of at least part of the coupling connecting that drive shaft tothe subsequent drive shaft of the bearing system.
 13. A method accordingto claim 10 in which the replacement bearing unit is introduced alongthe axis of the bearing unit housing and the part of the drive shaft ofthe replacement bearing unit closest to the first side of the barrierengages with the part of the bearing unit furthest from the second sideof the barrier.
 14. A system according to claim 1 in which the bearingsystem includes one motor, one or more drive shafts connecting the motorto the bearing unit and one or more drive shafts connecting the bearingunit to the equipment to be driven.
 15. A system according to claim 1 inwhich the bearing unit housing is provided with an aperture extendingfrom the first to the second side of the barrier which is of circularcross section and is of constant radius throughout at least the mid 90%of its length.
 16. A system according to claim 1 in which an increasedradius is provided for a portion of the bearing unit housing closest tothe first and/or second sides of the barrier.
 17. A system according toclaim 1 in which the bearing unit has a constant radius throughout atleast 80% of its axial length and the bearing unit has a reduced radiustowards the ends nearest the first and/or second sides of the barrier.18. A system according to claim 1 in which the drive shaft extendingthrough the bearing unit is provided with a male portion at one end, anda female portion at the other end.